package java8.optional;

import java.util.Optional;

public class Basic {
	public static void main(String args[]) {

		Basic java8Tester = new Basic();
		Integer value1 = null;
		Integer value2 = new Integer(10);

		// Optional.ofNullable - 允许传递为 null 参数
		Optional<Integer> a = Optional.ofNullable(value1);

		// Optional.of - 如果传递的参数是 null，抛出异常 NullPointerException
		Optional<Integer> b = Optional.of(value2);
		System.out.println(java8Tester.sum(a, b));
		
		Optional<User> userOp = Optional.ofNullable(new User("a", "ran"));
		userOp.filter(t->t.getName().equals("ran")).ifPresent(System.out::println);
		System.out.println(userOp.map(User::getName).get());
	}

	public Integer sum(Optional<Integer> a, Optional<Integer> b) {

		// Optional.isPresent - 判断值是否存在

		System.out.println("第一个参数值存在: " + a.isPresent());
		System.out.println("第二个参数值存在: " + b.isPresent());

		// Optional.orElse - 如果值存在，返回它，否则返回默认值
		Integer value1 = a.orElse(new Integer(0));

		// Optional.get - 获取值，值需要存在
		Integer value2 = b.get();
		return value1 + value2;
	}
	private static class User{
		private String id;
		private String name;
		public User(String id, String name) {
			super();
			this.id = id;
			this.name = name;
		}
		public String getId() {
			return id;
		}
		public void setId(String id) {
			this.id = id;
		}
		public String getName() {
			return name;
		}
		public void setName(String name) {
			this.name = name;
		}
	}
}
